Ford has officially announced that the 2014 Fiesta using the new and very small three-cylinder 1.0-liter EcoBoost engine is officially the most fuel-efficient non-hybrid vehicle in America. The little 1.0-liter engine is able to achieve 32 mpg in the city, 45 mpg on the highway, and 37 mpg combined.

Those official fuel efficiency ratings are dead on with Ford's promise of achieving mid-40 mpg efficiency when it first announced the tiny three-cylinder engine in November 2012. Ford says that the Fiesta is the only subcompact in its class able to deliver 45 mpg on the highway while producing over 120 hp.

Ford says that its 1.0-liter Fiesta achieves fuel efficiency of 12 mpg higher than the Honda Fit and 8 mpg higher than the Toyota Yaris on the Highway. The 1.0-liter EcoBoost Fiesta gets better fuel efficiency than some competitors’ diesel and hybrid vehicles. Ford specifically calls out the 2014 Honda Insight, which achieves 44 mpg on the highway and the 2014 VW Golf diesel with a manual transmission that achieves 42 mpg on the highway.

Despite being incredibly fuel-efficient, the 1.0-liter EcoBoost engine reduces 123 hp and 125 pound-foot of torque. The vehicle also features an overboost setting allowing the car to make 145 pound-foot of torque for up to 15 seconds.

The 2014 Ford Fiesta with the 1.0-liter EcoBoost is set to hit dealer showrooms later this year.

Power per unit of displacement is not a useful measure of engine efficiency. It's like measuring CPU performance by performance per clock tick. "Who cares? What matters is performance per watt or total performance."

Power per unit of weight or or per unit of useable engine volume is much better.For example, Corvette push-rod engines get much less power "per liter" than comparable DOHC engines, but push-rod engines are shorter and can be lighter, so Chevrolet is able to fit a more powerful engine in the same engine compartment than a comparable DOHC.Thus, when

quote: Power per unit of weight or or per unit of useable engine volume is much better. For example, Corvette push-rod engines get much less power "per liter" than comparable DOHC engines, but push-rod engines are shorter and can be lighter, so Chevrolet is able to fit a more powerful engine in the same engine compartment than a comparable DOHC.

Wow, straight from GM's mouth. I bet that tastes nasty.

If OHV designs were great, everyone manufacturer would use them in their cars. The fact that GM and Chrysler are the only two in the world hanging onto them (and as I recall went bankrupt)...that should tell you something.

quote: I can guarantee you that a 3-liter engine that had the same horsepower rating would be far less efficient.

That may not be the case at all. RPM is one of the major factors in fuel consumption and a larger engine that can produce the same power at a lower RPM will probably have a lower specific fuel consumption.

There will be a few facts in favor of a larger, lower-revving engine.

1. HP is (torque x rpm) /52522. Torque is proportional to displacement and compression ratio3. A higher compression ratio results in improved fuel economy.4. A forced induction engine needs to run a lower compression ratio than a naturally aspirated engine to stave off detonation.

If they made a naturally aspirated engine that produced those numbers at a lower RPM they could probably make it more efficient.

It's a fallacy that a smaller turbocharged engine is more efficient than a larger naturally aspirated engine. Ford claimed that with their V6 Ecoboost F-150 but then Chevy's new Silverado got better fuel economy with their naturally aspirated V8.

When the last generation Prius was being designed they moved to a larger engine so that they could improve fuel economy. (from the Prius Wikipedia article)

Also, the larger, heavier, and more powerful Mazda 3 still manages to get 41 mpg with its NA 2.0 liter engine that is twice the size of this 1.0 liter engine.

I think the main contributing factor to increased MPG is the advent of direct injection. It lets automakers use a much higher compression ratio than they'd normally be able to use. Ford's Ecoboost line was one of the first engine lines to use direct injection and they attributed the increased efficiency on the smaller size and turbocharging. Yet when competing automakers implemented direct injection on their own engine lines efficiency improved even more without having to use smaller engines or turbocharging. Case in point the direct-injected Silverado I previously mentioned.

Also, the Mazda 3 with direct injection gets better fuel economy than their smaller Mazda 2 even though that car is smaller, lighter, and has a smaller engine with only 2/3rds the power.

Allow me to set up a real-world scenario. A few years back our family had several cars, including a Nissan Sentra (1.6L 4-cylinder engine) and my old '69 Vette with a 427 (7L).

Now suppose I match the Sentra's horsepower by removing the quadrajet and installing a tiny one-barrel carb. Then I drop the 427 into the Sentra (good luck with that, but whatever). Assume both engines weigh the same.

It should be intuitively obvious that the 427 will be far less "efficient" as measured by overall fuel economy, even though both engines have the same horsepower. Why? Because throughout the operating region the 427 will have a far worse sfc than the little engine.

The Corvette will get better fuel economy on the highway and nearly the same on combined driving. And that's with a 455 HP, 6.2L V8... an engine that's more than twice the displacement and twice the power.

You are right. I have a 2.4L eclipse and my brother in law has a 3.0L galant, and his engine has about 1,800RPM at 65MPH while my engine with bigger pistons and fuel line injections, has about 2,600RPM @ 65MPH. My car is a gas guzzler compared to his car in typical usage scenario, as far as he doesn't push the gas pedal all the way down of course, and both are Mitsubishi based on the same platform.

I disagree. RPM is not a major factor in fuel consumption. Engine load is.

If RPM was a major factor, motorcycles would be gas guzzlers. Last time I checked, my 2-cylinder Honda CMX250 gets 80mpg cruising at 6000RPM. The simple reason is the load on the engine is minimal because there is less weight to pull.

The reason the Fiesta is getting this phenominal fuel economy, especially compared to hybrids, is because it's a tiny car with a tiny engine and the curb weight is going to be around 2500lbs. For comparison, the Golf TDI and Honda Insight they compared it to are 4200lbs and 2900lbs respectively.

And the reason your Eclipse gets weak fuel economy compared to a Galant is because the eclipse is tuned as a sports sedan and the Galant is tuned as a family sedan. The tuning means everything. Compare numbers from a Celica to a Camry and you'll see even with the same engine, the Camry is 15% more efficient even while being 400lbs heavier.

Tuners and eco-modders can attest to engine load being the primary factor for fuel consumption, however, gearing is matched specifically to a certain engine for a reason.

Depending on the design and type, each engine has a power band which will produce optimal efficiency, and gearing is used to take advantage of that. Running anywhere outside of the power band will consume more fuel when given a constant load; higher RPM or lower . The dynamics narrow in at higher MPH due to air drag, internal frictions, wheel inertia, tire drag, etcetera.

Way too many variables in play to make those generalizations. Transmission is a HUGE enabling factor--just ask those manual LS6 owners who got spanked by an AUTOMATIC making less HP (SLK55 AMG).

Compression ratio on a boosted engine isn't the same from one car to the next. There are OEM cars with FI that have the same compression ratio as OEM n/a cars. This is especially true when we're talking about factory OEM compression ratio for an engine designed to run on 87 octane.

The new Silverado v8 makes LESS power than the ecoboost v6:

Silverado: 355hp/383tq -MPG: 16city, 23hwy, 19combined-2WD

Ecoboost V6: 365hp/420tq -MPG: 17city, 21hwy, 19combined-2WD

It's very important to consider all the facts before passing judgment. There's a HUGE reason why the 3.5L ecoboost has sold like hotcakes in the F-150. Additionally, if you drive a turbocharged engine without being in boost--your fuel economy will very good (in most applications). Most V8's have to resort to cylinder deactivation to generate the kind of fuel-economy that is the natural territory of a boosted v6.

P.S.

V6's package easier than V8's in almost any type of vehicle. Additionally--all things being equal--when direct injection, variable valve timing, etc is applied to an FI v6 & an n/a v8, the v6 will almost universally put out higher power than the v8--even when restricted to mild boost.

Uh...This thing doesn't get much better mileage (better city/worse highway) than the Cruze Eco Diesel is rated at. And I'm betting the diesel can get better than advertised fuel economy. Especially once people start tuning them. You're not going to get much more out of a 1.0L gas engine.

Diesel weighs 15% more per gallon than gasoline, meaning it simply concentrates a greater amount of fuel (energy) into a smaller volume. Its energy density per volume is about 12% higher than gasoline, so divide all those diesel mileages by 1.12 to get a fair comparison of how far the car is going on the same amount of energy.

This is the reason planes and rockets measure fuel quantity by mass. That eliminates fuel density as a factor (which can change with capricious things like temperature). Unfortunately we measure car fuel economy in MPG, when lbs per 100 miles would be a much better measure.

In a 4-cycle engine, torque scales with displacement. Since diesel engines produce much more torque than petrol engines, the added weight of diesel doesn't take a hit on overall efficiency as it would on a petrol engine.

"The "per liter horsepower" argument is completely meaningless. Nobody cares how much power you got out of x.x liter engine- they only care about the end result."

The end result is an economy car that gets great mileage and has a decent power/weight ratio for an economy car , especially considering the mileage you get. Not every car is designed to be a sports car. this car achieves its goal very nicely and is extremely impressive in its market class.

My point was about the engine displacement, power, and efficiency. Nobody is arguing that this isn't an economy car.

Also, its market class is a tiny one. I don't really think that Ford (or any automaker really) is pushing this class of cars in the US. When I went to the Ford dealer they had Fiestas on sale for $17k while they had the Focuses discounted for $16,500. The Focuses had the newer direct injection engines while the Fiestas still had the older engines. You got less for more money. It was obvious that Ford wanted to push consumers toward the Focus since the Fiesta just isn't a good deal. And the sales reflect that.

In 2012 they sold 56,775 Fiestas and 245,922 Focuses in the US.

Same with Mazda. The larger Mazda 3 is more efficient and about the same price as than the "economical" Mazda 2.

I just want to chime in my first two cars were a Ford Escort with a 1.9l (77hp) and a Mazda Protégé 1.5l (96hp) and both were incredibly capable for their weight. Granted, both were manuals, and you pretty much had to floor it all the time to produce adequate power, but that's just how you drive a small engine.

Ironically, they were both the same platform so handling dynamics, braking and ergonomics were nearly identical.

The only problem with small engines is automatic transmissions don't cooperate because slushboxes operate on the premise of torque (which there is none in low displacement) and obviously stop and go traffic with the A/C running can be brutal.

Anyone who can't merge onto any interstate with 120 HP in this light a car has no business with a driver's license. I drive a car almost twice as heavy with 200 HP, and the gas pedal has never been close to the floor. Moderate, steady acceleration from the top of the ramp is always enough. Cars just don't need the horsepower most have these days. They are not toys.

You obviously don't have challenging ramps where you live or you would not laugh at drivers who require better torque figures. In Connecticut we have lots of entries that start at the bottom between two hills with Stop sign right before entering the highway, no merging lane (thanks to narrow bridge overpasses) and cars going at you down the hill at 75mph+.You essentially need to thread a needle into the oncoming traffic while accelerating from full stop and fighting gravity trying to climb a steep ascend.Add small light car that would be smashed to pieces from impact with virtually any self-respecting car on the highway and this would not be a laughing matter for you anymore.

My family's car in 1985 was a Honda Accord. Typical family sedan of that time, though it straddled the full size vs compact classification. 105 hp, 0-60 in 11 sec. We never had problems merging or passing.

No worse, really, than some vehicles built during the 80's, with much larger engines.

I remember having to drive a work truck that was a Dodge D-50 (rebadged Mitsubishi Mighty Max), when I was stationed in the San Francisco area. If you had to go over to Treasure Island Naval Station (middle of the Oakland-San Francisco Bay Bridge), God help you when you went to get back on the bridge, heading back toward Oakland, especially if you somehow squeezed 3 people into that truck cab!